The invention generally relates to an intramedullary nail. Particularly, the invention relates to polyaxial locking hole arrangement provided at an end portion of an intramedullary nail for a femur, a humerus or a tibia.
In the field of intramedullary nailing screw placement is very important in order to fixate different fracture patterns and to avoid damaging soft tissue.
U.S. Pat. No. 7,695,472 B2 discloses a bone plate with a longitudinal axis having a bone-contacting bottom side and a top side. Sets of overlapping holes communicate through the plate from the top to the bottom side. The overlapping holes have multifaceted surfaces such as a threaded surface or a coaxial series of annular groves. The sets of overlapping holes are adapted to receive a bone screw with a head and a bone-engaging thread.
U.S. Patent Publication No. 2006/0111716 discloses an intramedullary nail with a distal end suitable for an insertion into the medullar space, wherein the segment of the intramedullary nail facing the distal end has a diameter D, a proximal end, a central longitudinal axis, and several cross holes with a hole axis, each of which defines a virtual drill cylinder with a cylinder axis corresponding to the hole axis of the defining cross hole, wherein the drill cylinders of at least two cross holes penetrate each other, the cylinder axis of the two mutually penetrating drill cylinders have no common intersection point P on the longitudinal axis. The cylinder axis of the two mutually penetrating drill cylinders lies in a plane orthogonal to the longitudinal axis.
In general, the proximal end of the bone is the end of the bone being oriented toward the heart of the human body. The distal end of the bone is the end of the bone being oriented away from the heart of the human body. An intramedullary nail may be a femur nail, a humerus nail or a tibia nail, wherein the intramedullary nail comprises a non-driving end portion and a driving end portion. The non-driving end portion is the end of the nail which firstly enters the intramedullary channel of a bone. Entering a bone from the proximal end of the bone is denoted as antegrade entering. Entering a bone from the distal end of the bone is denoted as retrograde entering. Consequently, a nail adapted to be implanted from the proximal end of the tibia may be denoted as antegrade tibia nail, a nail adapted to be implanted from the distal end of the femur may be denoted as retrograde femur nail, and a nail adapted to be implanted from the proximal end of the humerus may be denoted as antegrade humerus nail.